Women and HIV in the United States

Women represent the fastest growing demographic of HIV infections worldwide. In order to work on reversing this trend, we must have a thorough understanding of the unique issues that affect women living with HIV infection. To date, the medical community has focused a large amount of its research efforts on HIV/AIDS in men.1,2 However, both clinical experience and the observational data that we do have suggest that, despite the many similarities between HIV-positive men and women, there are some sex/gender-related differences with important HIV prevention and treatment implications. These differences range from the interaction of HIV and the female immune system, to the social vulnerability that places women at higher risk for HIV and its complications. In order to design effective prevention and treatment strategies for HIV-positive women, we will need to understand and address any gender differences in the susceptibility to, and progression of, HIV infection. This article will review what we do know about women and HIV in terms of prevention and treatment, as well as highlighting areas that still require more research.

The Statistics

The statistics serve as a potent reminder that specific HIV prevention strategies for girls and women are greatly needed. Women represent 46% of all people in the world infected with HIV. However, the rate of new infections among women is climbing, with 50% of all new infections worldwide occurring in women (www.unaids.org). The United States has not escaped this global trend. The proportion of all AIDS cases in women has more than tripled in the past 15 years, from 7% in 1985 to 29% today.3

Women who are racial or ethnic minorities in this country are disproportionately at risk for HIV/AIDS. The Centers for Disease Control and Prevention (CDC) reports that, among HIV-positive women in the United States, over 80% are either African American or Hispanic. AIDS remains the leading cause of death in black women ages 25-34 in the U.S., while it represents the 10th leading cause of death in white women of the same age group.

The threat of death from HIV/AIDS remains high in older African American women as well: AIDS is the 3rd and 4th leading causes of death in black women ages 35-44 and 45-54 years old, respectively.4 Clearly, the rising rates of HIV infection in women and the disproportionate impact on women of color in this country require special attention.

Women May Be Unaware of Their Risks for HIV Infection

In order to prevent new HIV infection in women, we must first understand how women are being infected with HIV. According to many studies, approximately 40% of HIV-positive women report that they contracted HIV through sex with men. This number has not changed dramatically over the past two decades.

What has changed, however, is an increasing number of women who do not know how they got HIV. In one large study of over 2,000 HIV-positive women, 48% of participants could not identify how they had contracted HIV.5 Other studies have shown similar percentages of women not knowing how they contracted HIV, which likely indicates that women may not necessarily know the risk status of their male partners.6

A commonly-described phenomenon in the African American community, which may place black women at additional risk, is "down-low" behavior, where non-gay-identified men have secretive sex with other men and then unprotected intercourse with female partners.7 However, some analyses have shown that there is no real evidence that "down-low" behavior is fueling the epidemic among black women and that HIV prevention efforts in the African American community should not be focused on a single risk behavior.8

Because the majority of women in the United States acquire HIV through sex with men, often without any knowledge that they are at risk, prevention efforts in women must focus on increasing awareness of risk and routine diagnosis. Early diagnosis is critical to the prevention of HIV and AIDS.

We know that identifying HIV in an individual decreases the risk of him or her infecting somebody else because of behavior modification.9 HIV treatment also decreases a person's infectivity if he or she achieves undetectable viral loads. People who are diagnosed earlier also have a lower risk of progression to AIDS.

Unfortunately, an estimated 24?27% of people living with HIV in the United States are unaware of their status. Furthermore, according to a National Health Interview Survey conducted in 2007, only 36% of adults reported ever being tested for HIV.10

In hopes of strengthening HIV prevention efforts and maximizing the efficacy of treatment for HIV-positive individuals, the CDC published new recommendations in September 2006 that all adults aged 13-64 should be tested at least once for HIV in a medical setting and that people at higher risk should be tested annually.11 The guidelines recommend opt-out screening, where a patient would be informed that he or she will be tested for HIV infection and given the opportunity to decline, instead of the previously instituted opt-in screening, where written consent was required for testing. The guidelines relaxed requirements on written consent and pre-testing counseling, which can be both time and labor intensive, in the hopes that this would decrease barriers for HIV screening for both patients and providers.

These recommendations have not been fully implemented throughout the United States, since each state has needed to address the guidelines separately. California turned the CDC recommendations into law in 2007 with the passage of AB 682, which waives the need for written consent for HIV testing in this state. Widespread implementation of these recommendations would be especially beneficial to women in this country, given the lack of perceived risk factors for HIV in this population. [Also see "Doctors Urge the Government to Keep up With Medical Progress".]

HIV Prevention Strategies in Women

Women are biologically and sociologically more vulnerable to HIV infection than men. Women are at greater risk of HIV infection through heterosexual sex than are men simply by virtue of an unequal exchange of genital secretions. The risk of transmission of HIV from a man to a woman is approximately 1 in 1,000 for each sexual contact, whereas the risk of transmission from a woman to a man is much less (approximately one in 2,000).12

Women may also be at increased risk of infection during certain phases of their menstrual cycles (7-10 days following ovulation) because of hormonal interactions with the immune system,13 though further studies are needed on this topic.

Women living in both resource-rich and resource-poor settings are vulnerable to HIV infection through sex for a variety of reasons, often arising from positions of dependence and an inability to insist upon the use of male condoms.

Because women are more vulnerable to HIV through heterosexual sex, prevention efforts need to focus on providing women with female-controlled prevention modalities. Currently, the male condom is the most effective form of HIV prevention for people engaging in sex, followed by male circumcision in terms of specific protection for the male partner. Obviously, women have much less control over the use of a male condom during a heterosexual encounter than men. Women-focused methods for HIV prevention are listed in Table 1. Although the female condom does have some efficacy in reducing HIV transmission, it is not completely covert, as the outer ring or frame is visible outside the vagina. Further reducing its acceptability is the potential noise that the latex can make during intercourse. Additional hindrances to the use of the female condom include the fact that it is not readily available in many countries, can be difficult to insert and remove, can be more expensive than male condoms and historically, can be used only once.

Microbicides and diaphragms have received a lot of attention as they are relatively inexpensive and are completely female-centered modalities of prevention.

Diaphragms were studied with lubricant gel in a large randomized open-label controlled trial of 4,948 HIV-negative Zambian and South African women and showed no efficacy in protecting women against HIV transmission.14

Microbicides are biological or chemical substances that reduce transmission of HIV or other sexually transmitted diseases when applied to the vagina or rectum. Ideally a microbicide would be effective, safe with frequent use, widely available, easy to store and use, surreptitious, and acceptable to a variety of cultures. Most studies to date on different microbicide products, starting with the failure of nonoxynol-9 to protect women against HIV infection (and the possibility of increased transmission rates), have shown disappointing results in terms of interrupting transmission.

We are starting to see a new trend of better outcomes
in women compared to men.

A recent study has provided some hope for the field of microbicides and for the possibility of a female-controlled HIV prevention method at last. The interim safety and effectiveness results of a microbicide called PRO2000 (0.5%) were released at the 2009 Conference of Retroviruses and Opportunistic Infections (CROI) in Montreal, Canada a few months ago. PRO2000 (0.5%) is a highly negatively-charged molecule (a polyanionic polymer) that is designed to interfere with HIV entry into target calls. The HPTN035 trial was also designed to study another microbicide product (BufferGel) whose primary action is to lower vaginal pH levels. The trial enrolled 3,909 women from Malawi, South Africa, the United States, Zambia, and Zimbabwe, into four arms: the PRO2000 (0.5%) gel arm, the BufferGel arm, a placebo gel arm, and a no gel arm. The trial followed participants for a mean of 20.4 months.

Both microbicide products showed favorable safety profiles in the trial. While BufferGel did not show a protective effect against HIV, the trial indicated that PRO2000 was at least 30% more effective than any other arm in the study in preventing new HIV infections. This preliminary trial was not designed to generate definitive data on PRO2000, although the data is highly suggestive of the potential efficacy of this product. These findings were viewed with a great deal of enthusiasm in the microbicide and HIV prevention fields and other studies are underway. Studies that are looking at the efficacy of a once-a-day pill (tenofovir or tenofovir/emtricitabine) for HIV-negative people to protect themselves against HIV infection (the pre-exposure prophylaxis or PrEP trials) are also underway. [Also see What's Goin' On.]

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